March 27, 2008

Great Wall of China As Visible From Space

Stupid Question ™
Sept. 17, 1998
By John Ruch
© 1998

Q: Is it true the Great Wall of China is the only man-made object visible from space, and if so, why can’t you see I-70?

A: While other human-made objects—crops, reservoirs and city lights—are visible from space, no one up there has ever seen the Great Wall.

The wall is not “visible with the naked eye,” as we’ve been told so many times. In fact, it’s almost impossible to spot even with space cameras and in high-resolution satellite images.

NASA has no space photos of the Great Wall. According to Great Wall expert Arthur Waldron in his book “The Great Wall of China: From History to Myth,” US government charts based on aerial and satellite photos mislabel a road as part of the wall, and don’t show other known parts of the wall at all.

In contrast, the American Automobile Association was using Landsat satellite images to make road maps by the 1970s.

So where did this myth come from? And why do popular books and Chinese tour guides continue to repeat it?

It’s part of the greater myth that there is a Great Wall. As far as being a single structure with a unified purpose, the Great Wall of China doesn’t exist. It’s actually an umbrella term for many different walls that have never been fully surveyed.

In the late 18th and early 19th centuries, Western culture went bonkers for China and began wildly over-romanticizing its “Great Wall.” This combined improbably with the 1800s interest in astronomy and aliens at least as early as 1892, when the “Century Illustrated Monthly Magazine” said the wall is “the only work of man of sufficient magnitude to arrest attention in a hasty survey of the earth’s surface.”

William Edgar Geil, in his popular 1909 book on the wall, said it is a “great structure that some lunar inhabitants see like a black welt across the surface of the earth.”

In 1932, Robert Ripley’s “Believe It or Not!” cartoon column codified the idea by calling the wall “the mightiest work of man—the only one that would be visible to the human eye from the moon!” In the 1950s, alien-happy astronomers extended the supposition to say, “Ditto for Martian eyes!”

Meanwhile, NASA experts didn’t expect astronauts would see much on the ground on their first orbital flights—and they didn’t. How astronauts could be expected to see the wall from the Moon if they couldn’t from low orbit is a mystery. Yet as the Moon mission drew near, we were assured by pop authors that they would.

All you can see of Earth from the Moon is water, clouds, continents and general patches of vegetation. But still books like “The Great Wall” claim that astronauts saw the wall and “prove[d] empirically what everyone below had been saying.”

In 1994 NASA finally secured a clear view of the “Great Wall” from space—radar images taken by the space shuttle as part of a global mapping program. Even then, the wall was noticed only when the program head specifically looked for it—apparently inspired by the old myth.

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